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SubjectRe: [RFT][PATCH v2] backlight: 88pm860x_bl: Add missing of_node_put()
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On Sun, Jan 27, 2013 at 8:58 PM, Axel Lin <axel.lin@ingics.com> wrote:
> of_find_node_by_name() returns a node pointer with refcount incremented, use
> of_node_put() on it when done.
>
> of_find_node_by_name() will call of_node_put() against the node pass to from
> parameter, thus we also need to call of_node_get(from) before calling
> of_find_node_by_name().
>
> Signed-off-by: Axel Lin <axel.lin@ingics.com>
> ---
> v2:
> need to call of_node_get(pdev->dev.parent->of_node) before calling
> of_find_node_by_name().
>
> drivers/video/backlight/88pm860x_bl.c | 5 ++++-
> 1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/video/backlight/88pm860x_bl.c b/drivers/video/backlight/88pm860x_bl.c
> index c072ed9..2cd6350 100644
> --- a/drivers/video/backlight/88pm860x_bl.c
> +++ b/drivers/video/backlight/88pm860x_bl.c
> @@ -165,8 +165,10 @@ static int pm860x_backlight_dt_init(struct platform_device *pdev,
> struct pm860x_backlight_data *data,
> char *name)
> {
> - struct device_node *nproot = pdev->dev.parent->of_node, *np;
> + struct device_node *nproot, *np;
> int iset = 0;
> +
> + nproot = of_node_get(pdev->dev.parent->of_node);
> if (!nproot)
> return -ENODEV;
> nproot = of_find_node_by_name(nproot, "backlights");
> @@ -184,6 +186,7 @@ static int pm860x_backlight_dt_init(struct platform_device *pdev,
> break;
> }
> }
> + of_node_put(nproot);
> return 0;
> }
> #else

Don't agree on this. If we want to protect it, we should use the logic in below.
1. of_node_get() in parent 88pm860x-core driver.
2. of_node_put() in child backlight driver or anything else.

The reference is used to prevent of_node releasing before some usage.
At here, we need
to prevent parent driver to release of_node. I can't see any benefit
from of_node_get()
in the child backlight driver.

Regards
Haojian


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